1. Field of the Invention
The invention relates to an etching method for semiconductor, more particularly to an etching method for nitride semiconductor.
2. Description of the Prior Art
At present, the Light Emitting Device (L.E.D.) has become a revolutionary photoelectric product developed by semiconductor process after the development of transistor and laser diode. It is more worth to notice that high brightness gallium nitride (GaN) semiconductor has become one of main element materials of Light Emitting Device.
Thus, as for the manufacturing technology of Light Emitting Device, the traditional semiconductor manufacturing technology has been greatly applied. As for the known technology of semiconductor manufacturing, the dry etching has highly danger of Ion-Bombardment Damage, and it is not apt to get the smooth surface. It also has the adverse effect on the technological development of gallium nitride (GaN) Light Emitting Device.
So comparatively speaking, the wet etching technology has lower danger of Ion-Bombardment Damage, and its cost is relative low, which makes wet etching technology is adopted in Light Emitting Device largely and widely.
In the known art, U.S. Pat. No. 6,355,497 of “Removable large area, low defect density films for led and laser diode growth” used the Epitaxial Lateral Overgrowth (ELOG) method to grow Group III—nitride film, then used the chemical etching method to etch the dielectric layer to get the object of peeling Group III—nitride film from the substrate.
In addition, in the known art, U.S. Pat. No. 7,097,920 of “Group III nitride based semiconductor substrate and process for manufacture thereof” used the Pendeo Epitaxial Lateral Overgrowth (PENDEO) method to grow thick gallium nitride film on Sapphire substrate, then used the molten potassium hydroxide (molten KOH) to etch gallium nitride to get the object of peeling thick gallium nitride film from Sapphire substrate.
In the comparison, although the above-mentioned patents have basic test study on the etching way of wet etching for molten potassium hydroxide and gallium nitride, it is still not clear about the mechanism for the peeling of gallium nitride from the substrate, and it can not get required semiconductor structure after the etching process. Therefore, it is unable to become the main requirement of semiconductor process.